SWOC warns Thailand of heavy rain as south-west monsoon strengthens
The Royal Irrigation Department says Thailand faces continued rain and isolated heavy downpours, especially in the East and the South's west coast.
- Thailand's Smart Water Operation Centre (SWOC) has issued a warning for heavy rain as the south-west monsoon over the Andaman Sea and Gulf of Thailand strengthens.
- The strengthened monsoon, combined with a monsoon trough, is expected to cause persistent rain and isolated heavy downpours, particularly in the East and on the South's west coast.
- The period of increased rainfall is forecast from June 30 to at least July 6, with authorities advising those in at-risk areas to monitor for flash floods and landslides.
The Smart Water Operation Centre (SWOC) of the Royal Irrigation Department has issued an update on the water and weather situation for Tuesday (June 30, 2026), saying Thailand continues to see persistent rain and isolated heavy downpours, particularly in the East and the South's west coast.
People in at-risk areas are advised to closely monitor flash floods and forest run-off.
Citing information from the Thai Meteorological Department, the Office of the National Water Resources (ONWR) and the Weather Research and Forecasting (WRF) model, the update said the south-west monsoon covering the Andaman Sea, Thailand and the Gulf of Thailand was beginning to strengthen.
At the same time, the monsoon trough lies across the upper North and upper Laos into a low-pressure cell over upper Vietnam, bringing scattered thunderstorms to many parts of Thailand.
Closer look at rainfall trends, Tuesday (June 30, 2026) to Monday (July 6, 2026), from the WRF model
Analysis from the WRF weather model divides the monitoring period into two phases as follows:
Phase 1: Tuesday (June 30, 2026) to Friday (July 3, 2026) (monsoon trough over Thailand)
Situation: The monsoon trough continues to lie across the North and the upper North-east, combined with a fairly strong south-west monsoon.
Heavy rain areas: Thailand will see scattered thunderstorms, with isolated heavy rain, especially in the East and the South's west coast.
Phase 2: Saturday (July 4, 2026) to Monday (July 6, 2026) (rain continues)
Situation: The monsoon trough is expected to begin shifting northwards across the upper North, Laos and upper Vietnam, while Thailand remains under the influence of a fairly strong south-west monsoon covering the Andaman Sea and the Gulf of Thailand.
Impact: Many areas will continue to see rain, and isolated heavy rain will still need to be monitored.
Precautions and high-risk areas requiring special monitoring
The Royal Irrigation Department and relevant agencies have advised people in at-risk areas to prepare for volatile weather conditions, with areas requiring close monitoring including:
- Hillside slopes (risk of landslides and forest run-off)
- Low-lying areas (risk of insufficient drainage)
- Areas along waterways and urban communities (risk of accumulated flooding)
Public advice: People should closely follow official weather forecasts and water situation updates during this period to reduce possible loss of life and damage to property from natural hazards.
Source: Bangkokbiznews
